To understand the causes and consequences of health care intensity, it is crucial to understand whether such differences across regions are associated with patient preferences, physician behavior, or other factors and, second, whether patients actually prefer the greater health care intensity. To date, there is fragmented evidence on these important questions. In this Core, three innovative data acquisition and processing strategies are described that provide the information necessary to address these questions. 1. The development and fielding of a broad-scope telephone survey to elicit patient experience with screening, testing, and treatment options, as well as patient opinions about whether the surveillance and care they receive is more or less aggressive than they would like. This survey will include a re-sampling after two years to determine changes in the level of intensity of care actually received, in functional level, and in screening, testing, and treatment preferences. 2. In many cases, it is difficult to get full measures of tradeoffs among different patient options over the phone. To address this issue, a focused in-person interview strategy is planned that uses explicit tradeoff techniques to elicit patient preferences with regard to different degrees of intensity of screening, testing, and treatment. 3. To better understand the causes of variation in health care intensity across regions, a survey of primary care physicians and cardiologists is planned. This survey would elicit information on their beliefs about the value of aggressive testing in general and about treatment for cardiovascular disease and cancer in particular, their beliefs about the appropriate way to manage end-of-life care, and their assumptions about the appropriateness of the kind of care they provide in their own practices.